Treatment process for preparing high-quality industrial grease from waste grease through whole-process processing

Abstract

The invention provides a treatment process for preparing high-quality industrial grease from waste grease through whole-process processing, and relates to the technical field of waste grease treatment. Double-tower continuous rectification operation is adopted, the characteristic that sulfur, chlorine, metal ions and part of colloid substances are mainly distributed in light components or heavy components can be utilized, and through the optimized two-tower structure and operation conditions, the light components with high impurity component content are continuously extracted from the top of the first tower, and the heavy components with high impurity component content are continuously extracted from the bottom of the second tower; and oil phase products with qualified indexes can be continuously obtained at the tops of the two towers, and the double-tower operation has the advantage that the defect that the single-tower operation cannot simultaneously meet the quality of materials extracted from the tower top and the tower kettle is overcome. The treatment process for preparing the high-quality industrial grease through the whole-process processing of the waste grease, provided by the invention, has the advantage that the primary waste grease raw material can be processed to meet the advanced grease quality index requirements through optimal combination of various unit operations.

Description

Technical Field

[0001] The invention relates to the technical field of waste grease treatment, and in particular to a treatment process for preparing high-quality industrial grease through full-process processing of waste grease. Background Art

[0002] Waste oil is the main raw material for renewable energy - biodiesel. Domestic and foreign research data show that for every ton of biodiesel used, 2-2.5 tons of carbon dioxide emissions can be reduced. In 2009, the European Union passed the Renewable Energy Directive. In 2018, the second version of the Renewable Energy Directive was passed, requiring that by 2030, the proportion of renewable fuels in road transport fuels should be 14%, and advanced biofuels (advanced biofuels) should be divided into Part A and Part B. The blending ratio of Part A in 2030 must reach 3.5% (double counting, the actual effect is 1.75%). The upper limit of advanced biofuel Part B in 2030 is 1.7%. After the promulgation of the ILUC directive, the EU began to restrict food-based biodiesel and stipulated that waste oil has the highest emission reduction effect. The 2016 Winter Package proposal even stated that the proportion of food-based biodiesel would be limited to 3.8% (far below 7%) in 2030, and the proportion of advanced biofuels would be increased to 6.8%.

[0003] Due to the continuous upgrading of biodiesel quality indicators and the limitations of its production process, higher quality requirements have been gradually put forward for waste oil raw materials, especially chlorine, phosphorus, sulfur, metal ions, unsaponifiable matter and other indicators are constantly improving. However, due to the complex sources of waste oil, uncertain components, and non-uniform processing technology, the quality indicators vary greatly, especially for the above indicators. The requirements are relatively high, and traditional treatment methods can hardly make the product quality meet the standards.

[0004] A method for pretreating waste oil with high chlorine content is disclosed in the prior art, and the steps are: A process: waste animal and plant oils → adsorption → hydrolysis → continuous drying or continuous distillation; or B process: waste animal and plant oils → acid treatment → liquid separation → drying → adsorption → hydrolysis → continuous drying or continuous distillation to pretreat waste oils according to the different total metal + phosphorus content in the raw materials. However, the above method has the following problems: 1. The process route is incomplete and is not suitable for the initial waste oil raw materials with high water content. Since the excessive moisture and mechanical impurities are not removed first, the effect of subsequent adsorption or acid treatment operations is affected. 2. The acid treatment unit uses inorganic acid, which increases the difficulty of sewage treatment and may pollute the environment. 3. The hydrolysis process uses a medium-high pressure process with high temperature and high pressure, which is easy to lead to high energy consumption and blockage of the heat exchanger, resulting in uncontinuous production. 4. The distillation unit adopts a single tower operation. In theory, it is impossible to separate the impurity components in the top product from the main product, but it may increase the content of impurity components such as sulfur, chlorine, and metal ions in the main product.

[0005] Therefore, it is necessary to provide a new full-process processing technology for waste oil and fat to prepare high-quality industrial oil and fat to solve the above technical problems. Summary of the invention

[0006] The technical problem solved by the present invention is to provide an optimized combination of multiple unit operations, which can process the most basic waste oil raw materials into a processing technology for preparing high-quality industrial oil through the whole process of waste oil that can meet the requirements of advanced oil quality indicators.

[0007] In order to solve the above technical problems, the present invention provides a process for preparing high-quality industrial grease from waste grease by full-process processing, which includes:

[0008] S1: gradually heat the waste oil in the reactor R01 to 85±5℃ and keep the stirring speed at 15-40r / min, then pump the mixture into the three-phase horizontal spiral centrifuge L01 for three-phase separation of oil, water and residue;

[0009] S2: Add water at a ratio of 5-20% to the oil phase material separated in S1 in the reactor R02, turn on the steam and heat it to 110-130°C, add the composite acid catalyst A at a ratio of 0.5-5%, and react for 1-4 hours. Then turn off the steam and let it stand for 1-3 hours, open the bottom valve to drain the lower water phase and the middle turbid layer, repeat this step 2-3 times until the acid value of the oil phase material no longer increases significantly, and the upper oil phase material is obtained by sedimentation separation;

[0010] S3: The oil phase material separated in S2 is pumped into the vacuum drying tower T3 for flash dehydration at an absolute pressure of 3-8 kPa and a temperature of 110-130°C. The moisture content of the material after dehydration is <0.1%;

[0011] S4: The vacuum-dried oil phase material in S3 is transported to the reactor R03, and the composite adsorbent B is added at a ratio of 1-3% under the conditions of a temperature of 110-130°C and an absolute pressure of 3-8kPa. After continuous stirring for 0.5-1 hour, the mixture is pumped into the plate-type closed filter L02 to complete solid-liquid separation to obtain a clarified oil phase material;

[0012] S5: The clarified oil phase material obtained in S4 is fed into the middle part of the distillation tower T1, the feed temperature is 150-190°C, the bottom material is circulated and heated to 200-240°C through the falling film reboiler at the bottom of the tower, and the vaporized material in the tower completes the heat and mass transfer process with the descending condensate of the built-in condenser E101 at the top of the tower while ascending through the lower and upper fillers. After the gas passes through the condenser E102, it is collected in V01 to obtain the light component material rich in sulfur and metal ions;

[0013] S6: The material that has undergone the first delightening is sent to the distillation tower T2. The feeding position is the bottom of the distillation tower T2. The bottom material of the distillation tower T2 is heated by the bottom falling film reboiler E104 and then returned to the bottom of the tower. The top gas phase is collected in V02 through the external condenser E103 to obtain the finished product material with qualified key indicators such as sulfur, chlorine, and metal ions. The bottom of the distillation tower T2 continuously outputs the bottom concentrated material rich in sulfur and metal ions.

[0014] Preferably, the composite acid catalyst A in S2 comprises acetic acid and methanesulfonic acid, and the ratio of the acetic acid to the methanesulfonic acid is 4:1.

[0015] Preferably, in S4, the composite adsorbent B comprises activated clay and activated carbon, and the ratio of the activated clay to the activated carbon is 4:1.

[0016] Preferably, in S5 and S6, a double distillation tower series operation mode is adopted, and at the top of the distillation tower T1, light components enriched with characteristic components such as sulfur and metal ions are continuously produced, and then at the top of the T2, oil products with qualified indicators are continuously produced, and at the same time, the tower bottom concentrated material containing sulfur and metal ions is output in the tower bottom.

[0017] Preferably, in S5, the vacuum degree of the top of the distillation tower T1 is 3.5-4.5 kPaA, and the vacuum degree of the bottom of the distillation tower T1 is 4.5-5.5 kPaA; the distillation tower T1 is a desulfurization and delightening distillation tower, and the lower packing type is a large-diameter random packing; the upper packing type is a metal wire mesh structured packing.

[0018] Preferably, the minimum number of packing plates of the desulfurization and delightening distillation tower is 7-8, and the optimal reflux ratio of the desulfurization and delightening distillation tower is 2.0.

[0019] Preferably, in S6, the material that has undergone a light removal is sent to the distillation tower T2, and the feeding position is the bottom of the distillation tower T2, that is, the tower only retains the upper distillation section and removes the lower conventional stripping section to ensure that abnormal conditions caused by packing blockage that may be caused by coking and carbon deposition at high temperature can be avoided.

[0020] Preferably, in S6, the bottom temperature of the distillation tower T2 is 220-250°C, the vacuum degree of the top of the tower is 1.5-2.5 kPaA, and the vacuum degree of the bottom of the tower is 2.5-3.5 kPaA.

[0021] Preferably, the packing type of the upper section of the feed inlet of the distillation tower T2 is a metal wire mesh structured packing.

[0022] Preferably, the minimum number of packing plates of the distillation tower T2 is 5-6; and the optimal reflux ratio of the distillation tower T2 is 1.7.

[0023] Compared with the related art, the processing technology for preparing high-quality industrial grease from waste grease provided by the present invention has the following beneficial effects:

[0024] The present invention provides a processing technology for preparing high-quality industrial grease from the whole process of waste oil and fat. The continuous operation of double distillation towers can utilize the characteristics that sulfur, chlorine, metal ions and some colloid substances are mainly distributed in light components and heavy components. Through the optimized operating conditions of the two towers, such as temperature, pressure, reflux ratio and other operating parameters, the light components with high content of the above-mentioned impurity components are continuously extracted at the top of one tower, and the heavy components with high content are extracted at the bottom of the second tower, and it is ensured that the oil phase products with qualified indicators can be continuously obtained at the top of the second tower. The advantage of the double tower operation is that it overcomes the disadvantage that the single tower operation cannot simultaneously meet the quality of the materials extracted from the top of the tower and the kettle, and also avoids the situation that the single tower can meet the requirements of the quality indicators through the re-evaporation method, but the energy consumption is forced to increase. It is an optimal solution; for the most typical primary waste oil and fat, after the above-mentioned continuous unit operation, an oil product that meets the "advanced oil quality requirements" can be obtained. Each unit operation has its own purpose and is also a preparatory step for the next unit operation, and they are interconnected and organically combined. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A flow chart of the processing technology for preparing high-quality industrial grease through the whole process of waste grease provided by the present invention;

[0026] Figure 2 is the reaction equation for oil hydrolysis;

[0027] Figure 3 It is the quality index of biodiesel feedstock;

[0028] Figure 4 The simulation calculation and pilot test data comparison diagram of the number of theoretical plates of the distillation tower T1 for the whole process of processing waste oil and fat to prepare high-quality industrial oil and fat provided by the present invention;

[0029] Figure 5 The simulation calculation and pilot data comparison of the reflux ratio of the distillation tower T1 for the whole process of waste oil and fat processing to prepare high-quality industrial oil and fat provided by the present invention;

[0030] Figure 6 The simulation calculation and pilot data comparison of the theoretical plate number of distillation tower T2 for the whole process of waste oil and fat processing to prepare high-quality industrial oil and fat provided by the present invention;

[0031] Figure 7 The simulation calculation and pilot data comparison of the theoretical plate number of distillation tower T2 for the full-process processing of waste oil and fat to prepare high-quality industrial oil and fat provided by the present invention. DETAILED DESCRIPTION

[0032] The present invention will be further described below in conjunction with the accompanying drawings and implementation modes.

[0033] Please refer to Figure 1-3 The present invention provides a process for preparing high-quality industrial grease from waste grease by full-process processing, which includes the following steps:

[0034] Step 1: gradually heat the waste oil in the reactor R01 to temperature t1 (85±5℃) and maintain a certain stirring speed r1 (15-40r / min), and then pump the mixed material into the three-phase horizontal spiral centrifuge L01 for oil-water residue separation. The purpose of this unit is to separate the water and mechanical impurities contained in the initial raw oil to the greatest extent, so as to ensure the use effect of the catalyst in the subsequent reaction.

[0035] Step 2: Add water to the oil phase material obtained by the above separation in R02 according to the ratio a1 (5-20%), turn on the steam to raise the temperature to a certain temperature t2 (110-130°C), and add the composite acid catalyst A (acetic acid: methylsulfonic acid = 4:1) according to the ratio a2 (0.5-5%). The reaction time is b1 (1-4) hours, then turn off the steam and start to stand for b2 (1-3) hours, open the bottom valve to drain the lower water phase and the middle turbid layer. Repeat this step c (2-3) times until the acid value of the oil phase material no longer increases significantly, and the upper oil phase material is obtained by sedimentation separation. The purpose of this unit is to transform hydrated phospholipids (HP), oil-soluble non-hydratable phospholipids (NHP), proteins and other colloids into water-soluble substances through improved hydrolysis process conditions while hydrolyzing oils and fats, and then carry away most of them through the water phase through the process of oil-water separation, so as to achieve the purpose of separating such impurities from oily materials and reduce the content of related impurity components of oils and fats and the metal ions combined with them.

[0036] The reaction equation for oil hydrolysis is as follows Figure 2 As shown,

[0037] Acid degumming mechanism:

[0038] Under acidic conditions, non-hydratable phospholipids (NHP) in crude oil hydrolyze a fatty acid to generate hydratable substances, lysophospholipids, which can be removed from the oil by precipitation or centrifugation due to their good hydrophilicity. They can neutralize the charge of colloidal particles, causing them to aggregate and settle, and can also bind metal elements and achieve a certain decolorization effect.

[0039] Another advantage of the improved hydrolysis process is that the aqueous phase material obtained by the above separation is acidic. After being neutralized with NaOH to a pH of 6.8-7.4, the aqueous phase material can not only be easily treated by a conventional biochemical system, but also can be processed into a "carbon source" product for water treatment that must be used in sewage treatment equipment because it contains a relatively high concentration of sodium acetate. This fundamentally solves the wastewater treatment problem caused by the use of inorganic acids such as sulfuric acid and phosphoric acid in conventional hydrolysis processes, and can turn it into a renewable and environmentally friendly product.

[0040] Step 3: The oil phase material obtained by the above separation is pumped into the vacuum drying tower T3, and flash dehydration is carried out under the condition of absolute pressure of d1 (3-8) kPa and temperature of t3 (110-130°C). The water content of the material after dehydration is <0.1%. This unit process is a necessary preparatory step for the next adsorption operation.

[0041] Step 4: The above vacuum-dried oil phase material is placed in R03 at a temperature of t3 (110-130°C) and an absolute pressure of d1 (3-8) kPa, and a composite adsorbent B (activated clay: activated carbon = 4:1) is added in a ratio of a3 (1-3%). After the process is carried out in a stirred tank for b3 (0.5-1) hours, it is pumped into a plate-type closed filter L02 to complete solid-liquid separation and obtain a clarified oil phase material. The main purpose of this unit operation is to further remove the colloidal substances in the oil phase material by selecting a suitable adsorbent, while facilitating the subsequent distillation operation.

[0042] Step 5: The above oil phase material enters the middle of the distillation tower T1, the feed temperature is t4 (150-190℃), the bottom material is circulated and heated to t5 (200-240℃) through the falling film reboiler at the bottom of the tower, and the vaporized material in the tower completes the heat and mass transfer process with the descending condensate of the built-in condenser E101 at the top of the tower while rising through the lower and upper fillers. After the gas passes through the condenser E102, it is collected in V01 to obtain light component materials rich in sulfur and metal ions. The tower kettle also outputs the light-removed material to the distillation tower T2.

[0043] The vacuum degree of the top of distillation tower T1 is d2 (3.5-4.5) kPaA, and the vacuum degree of the bottom of the tower is d3 (4.5-5.5) kPaA

[0044] The above-mentioned distillation tower T1 is a desulfurization and light distillation tower, and the lower packing type is large-diameter random packing, and the typical selection is Saddle ring random packing. The upper packing type is wire mesh structured packing, the typical selection is BX500.

[0045] The above-mentioned distillation tower T1 is a desulfurization and delightening distillation tower, and the optimal theoretical plate number is e1 (7-8 plates); the optimal reflux ratio is: R1 (2.0).

[0046] Step 6: The above-mentioned light-removed materials are sent to the distillation tower T2. The feeding position is the tower kettle, that is, the tower only retains the upper distillation section and removes the lower conventional stripping section to ensure that the abnormal situation caused by the plugging of the packing due to coking and carbon deposition at high temperature is avoided. The materials in the T2 tower kettle are heated by the falling film reboiler E104 and then returned to the tower kettle. The gas phase at the top of the tower is collected in V02 through the external condenser E103 to obtain the finished product materials with qualified key indicators such as sulfur, chlorine, and metal ions. The tower kettle continuously outputs the tower kettle concentrated materials (vegetable asphalt) rich in sulfur and metal ions.

[0047] The operation mode of double distillation towers in series is adopted. The characteristic components of sulfur and metal ions enriched in the light components are distilled and separated in distillation tower T1, and then the fatty acids and glycerides are distilled and separated in T2.

[0048] The above-mentioned distillation tower T2 has a bottom temperature of t6220-250°C), a top vacuum of d4 (1.5-2.5) kPaA, and a bottom vacuum of d5 (2.5-3.5) kPaA.

[0049] In the above-mentioned distillation tower T2, there is no packing in the lower section of the feed inlet. The packing type in the upper section of the feed inlet is metal wire mesh structured packing, and the typical type is BX500.

[0050] For the above-mentioned distillation tower T2, the optimal theoretical plate number of packing is e3 (5-6 plates); the optimal reflux ratio is: R2 (1.7).

[0051] Compared with the related art, the processing technology for preparing high-quality industrial grease from waste grease provided by the present invention has the following beneficial effects:

[0052] The present invention provides a treatment process for preparing high-quality industrial grease from the whole process of waste grease. The continuous operation of double distillation towers can utilize the characteristics that sulfur, chlorine, metal ions and some colloid substances are mainly distributed in light components and heavy components. Through the optimized operating conditions of the two towers, such as temperature, pressure, reflux ratio and other operating parameters, the light components with high content of the above-mentioned impurity components are continuously extracted at the top of one tower, and the heavy components with high content are extracted at the bottom of the second tower, and it is ensured that the oil phase products with qualified indicators can be continuously obtained at the top of the second tower. The advantage of the double tower operation is that it overcomes the inability of the single tower operation to simultaneously meet the quality of the materials extracted from the top of the tower and the kettle, and also avoids the situation that the single tower can meet the requirements of the quality indicators through the re-evaporation method, but the energy consumption is forced to increase. It is an optimal solution; for the most typical primary waste grease, after the above-mentioned continuous unit operation, an oil product that meets the "advanced grease quality requirements" can be obtained. Each unit operation has its own purpose and is also a preparatory step for the next unit operation, and they are interconnected and organically combined.

[0053] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A process for preparing high-quality industrial grease from waste grease through the whole process, characterized in that: The following steps are involved: S1: gradually heat the waste oil in the reactor R01 to 85±5℃ and keep the stirring speed at 15-40r / min, then pump the mixture into the three-phase horizontal spiral centrifuge L01 to separate the oil, water and residue; S2: Add water in a proportion of 5-20% to the separated oil phase material in the reactor R02, turn on the steam to raise the temperature to 110-130°C, add composite acid catalyst A in a proportion of 0.5-5%, and react for 1-4 hours. Then turn off the steam and let it stand for 1-3 hours, open the bottom valve to drain the lower water phase and the middle turbid layer, repeat this step 2-3 times until the acid value of the oil phase material no longer increases significantly, and the upper oil phase material is obtained by sedimentation separation; S3: The separated oil phase material is pumped into the vacuum drying tower T3 for flash dehydration at an absolute pressure of 3-8 kPa and a temperature of 110-130°C. The moisture content of the material after dehydration is <0.1%; S4: Add composite adsorbent B in a proportion of 1-3% to the vacuum-dried oil phase material in a reactor R03 at a temperature of 110-130°C and an absolute pressure of 3-8kPa. After 0.5-1 hour, pump it into a plate-type closed filter L02 to complete solid-liquid separation to obtain a clarified oil phase material. S5: The oil phase material is fed into the middle of the distillation tower T1, the feed temperature is 150-190°C, the bottom material is circulated and heated to 200-240°C through the falling film reboiler at the bottom of the tower, the vaporized material in the tower passes through the lower and upper fillers, and then passes through the built-in internal reflux condenser E101 at the top of the tower, the temperature is 120-140°C, and passes through the condenser E102, and the light component material rich in sulfur and metal ions is collected in V01; S6: The material that has undergone the first light removal is transported to the distillation tower T2, and the feeding position is the bottom of the distillation tower T2. The bottom material of the distillation tower T2 is heated by the bottom falling film reboiler E104 and then returned to the bottom of the tower. The top gas phase is collected in V02 through the external condenser E103 to obtain the finished product material with qualified key indicators of sulfur, chlorine and metal ions. The bottom of the distillation tower T2 continuously outputs the bottom concentrated material rich in sulfur and metal ions; In the above-mentioned S5 and S6, a double distillation tower is connected in series, and the light component enriched with characteristic components of sulfur and metal ions is continuously produced at the top of the distillation tower T1, and then the oil product with qualified indicators is continuously produced at the top of the tower T2, and the tower bottom concentrated material containing sulfur and metal ions is outputted at the bottom of the tower; In S6, the light-removed material is sent to the distillation tower T2, and the feeding position is the bottom of the distillation tower T2, that is, the tower only retains the upper distillation section and removes the lower conventional stripping section to ensure that abnormal conditions caused by packing blockage caused by coking and carbon deposition at high temperature can be avoided.

2. The process for preparing high-quality industrial grease from waste grease according to claim 1, characterized in that: The composite acid catalyst A in S2 includes acetic acid and methanesulfonic acid, and the ratio of the acetic acid to the methanesulfonic acid is 4:

1.

3. The process for preparing high-quality industrial grease from waste grease according to claim 1, characterized in that: In S4, the composite adsorbent B includes activated clay and activated carbon, and the ratio of the activated clay to the activated carbon is 4:

1.

4. The process for preparing high-quality industrial grease from waste grease according to claim 1, characterized in that: In S5, the top vacuum degree of the distillation tower T1 is 3.5-4.5 kPaA, and the bottom vacuum degree of the distillation tower T1 is 4.5-5.5 kPaA; the distillation tower T1 is a desulfurization and delightening distillation tower, and the lower packing type is a large-diameter random packing; the upper packing type is a metal wire mesh structured packing.

5. The process for preparing high-quality industrial grease from waste grease according to claim 4 is characterized in that: The minimum number of packing plates of the distillation tower T1 is 7-8, and the optimal reflux ratio of the distillation tower T1 is 2.

0.

6. The process for preparing high-quality industrial grease from waste grease according to claim 1, characterized in that: In the above S6, the bottom temperature of the distillation tower T2 is 220-250°C, the vacuum degree of the top of the tower is 1.5-2.5 kPaA, and the vacuum degree of the bottom of the tower is 2.5-3.5 kPaA.

7. The process for preparing high-quality industrial grease from waste grease according to claim 1, characterized in that: The packing type of the upper section of the feed inlet of the distillation tower T2 is a metal wire mesh structured packing.

8. The process for preparing high-quality industrial grease from waste grease according to claim 1, characterized in that: The minimum number of packing plates of the distillation tower T2 is 5-6; the optimal reflux ratio of the distillation tower T2 is 1.7.

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